About the Gas Mileage Calculator
This gas mileage calculator divides the miles you drove by the gallons you used to get your car’s real-world MPG. It also estimates how much a road trip or your daily commute costs in gas, and converts fuel economy between US mpg, UK mpg, liters per 100 km and km per liter – handy when renting a car abroad or comparing European car specs.
How to use
- Enter the miles driven and the gallons used to get your MPG.
- Tap Use this MPG or type a fuel economy, then enter the gas price and trip distance.
- Add miles per day and driving days to estimate monthly and yearly fuel costs.
- Use the converter to switch between mpg, L/100 km and km/L.
MPG to L/100 km chart
| L/100 km | km/L | mpg (US) |
|---|---|---|
| 4 L/100 km | 25.0 km/L | 58.8 mpg |
| 5 L/100 km | 20.0 km/L | 47.0 mpg |
| 6 L/100 km | 16.7 km/L | 39.2 mpg |
| 7 L/100 km | 14.3 km/L | 33.6 mpg |
| 8 L/100 km | 12.5 km/L | 29.4 mpg |
| 10 L/100 km | 10.0 km/L | 23.5 mpg |
| 12 L/100 km | 8.3 km/L | 19.6 mpg |
How MPG is calculated
MPG = miles driven ÷ gallons used. L/100 km works the other way round – it shows fuel used per distance – so the conversion is a division: L/100 km = 235.21 ÷ mpg (US). A UK (imperial) gallon is about 20% larger than a US gallon, so UK mpg figures look higher for the same car.
FAQ
How do I calculate my gas mileage?
Fill the tank, reset the trip meter, drive normally, then fill up again. Divide the miles on the trip meter by the gallons you added. 300 miles ÷ 10 gallons = 30 mpg.
How do I convert mpg to L/100 km?
Divide 235.21 by the US mpg figure. 30 mpg ≈ 7.84 L/100 km.
How much does a 300-mile trip cost?
At 30 mpg you need 10 gallons; at $3.20 a gallon that is $32.
Why are UK mpg numbers higher?
The imperial gallon (4.546 L) is bigger than the US gallon (3.785 L), so the same car goes more miles per UK gallon.